1. Field of the Invention
This invention pertains to heat transfer, and more particularly to cooling and noise suppression of welding machines.
2. Description of the Prior Art
Engine driven welding machines produce considerable heat. Sources of the heat include the engine as well as various electrical components such as rectifiers, stabilizers, and generators. For effective operation of the welding machine, sufficient heat must be removed to keep the engine and electrical components at proper operating temperatures. The rectifier, stabilizer, and generator are usually the most critical electrical components that must be cooled because the output of the welding machine is limited by the rise in temperature of those components.
Some prior machines utilized different fans to produce separate air flows through the engine and electrical compartments. Other prior machines were designed such that the entire machine formed a single air-cooled plenum.
The prior cooling efforts were not completely satisfactory. Many of the air flow paths were quite short between intake and exhaust, with the result that some spaces of the compartments were not adequately cooled.
A related deficiency of the air cooling systems of prior welding machines concerned noise. The primary source of noise in an engine driven welding machine is caused by the mechanical and combustion noise of the engine. To a lesser degree, the generator also creates noise, especially its fan. Some of the mechanical and combustion noise of the engine can radiate through the cylinder walls and head into the engine compartment, and this noise needs to be either muffled or contained. In addition, this noise, especially the valve and combustion noise, can travel back up the intake manifold and through the air cleaner or intake passageway and out to the atmosphere. This is potentially a major source of noise.
The earliest way of cooling an engine driven welding machine was to leave it open to the atmosphere. In an attempt to reduce the noise, a box was built around the machine. Unfortunately, the box inhibited cooling and intake combustion air flow such that the welder could not be cooled or run efficiently. Accordingly, ducts were incorporated into the box in order to introduce air for combustion and cooling. However, the ducts allowed the escape of noise, unless the ducts were positioned and routed in such a way that the noise that was generated at one end of the ducts was reduced inside them. The ducts of prior welding machines were often too short and straight to have much success in reducing noise.